Folding scissors of various types have been known for many years and have long been included in multipurpose folding tools. In the past, most folding scissors in such multipurpose tools have been very small, and therefore relatively ineffective.
One type of folding scissors in a multipurpose tool is disclosed, for example, in Moser U.S. Pat. No. 696,995. In that type of tool one blade of a pair of scissors has an extended handle which is attached to pivot the entire pair of scissors into a storage slot in a knife handle. A second handle and its attached scissors blade are also stowed in the same slot, with the scissors blades and handles generally parallel with one another. A small leaf spring is typically used to urge the handles apart from each other to open the blades of such a pair of miniature scissors, and the spring is kept compressed when the scissors are in the stowed position. The spring typically used in such scissors is easily lost or accidentally bent to an inoperative condition.
East German Patent Publication 2,322,229 discloses another type of folding scissors using a long spring in a handle of a tool to move an auxiliary lever to urge a handle of a movable scissors blade in a blade-opening direction. This arrangement, however, fails to hold the handle of the main scissors blade stably fixed relative to the tool handle when the movable scissors handle and blade are urged in a blade-closing direction with respect to the main blade.
German Patent No. 145784 discloses a tool incorporating a folding handle with a pair of scissors blades which can be stowed within a multipurpose tool handle, but such scissors include the previously mentioned type of spring or none at all.
In previously-known folding scissors including a spring for opening the scissors blades, the force needed to move the blades in a closing or cutting direction has increased with continued closing movement of the blades. It is therefore desired to provide scissors which are easier to use in that the force needed to close the blades completely is not greatly increased over that required to close the blades partially during a cutting stroke of the scissors.
Many types of multipurpose pocket tools and pocket knives are known in which various knife blades, screwdrivers or other tool bits fold into storage locations within either a handle, or pair of handles. In some such multipurpose pocket tools, the handles are configured as channels of formed sheet metal that are able to pivot around the bases of a central pair of tool blades or jaws to reduce the size of the channel shaped handles as the outer surface of the folded tool.
In the case of previously known multipurpose folding hand tools, the typical channel-shaped handles do not provide spring pressure separately to each blade in order to hold it in the closed or open position. There is typically one spring, usually integral to the handle, which cannot hold all the blades contained within closed without some looseness. Therefore, the typical way to hold the blades closed is by side friction applied by the blade pivot pin. Blade looseness may allow the tips of the blades to open slightly, exposing the sharp and potentially dangerous edges. Side friction can sometimes be overcome by a jolt to the tool, causing the blades to unfold partially, exposing the sharp and potentially dangerous edges. The ideal side friction required for holding the blades in the channel-shaped handles without individual springs requires manual adjustment and is difficult to achieve. Channel-shaped handles are thus difficult to manufacture and assemble. For these reasons, it has become customary for good tool design to dictate that handles of a pair first be spread apart from each other in order to gain access to the blades contained within the handles. When the tool is folded closed, the opposite tool handles prevent the accidental partial opening of the blades.
In some pocket knives, the handles are configured as generally flat pieces of sheet metal which sandwich the various blades. Each blade pivots about a pin located at its base and is held either open or closed by an individual spring which must be supported at its base and near its center in order to provide adequate spring pressure. This center support is typically provided by a pin.
Each blade of a pocket knife typically has its own individual spring to bias it closed. This allows the blades safely to be located on the outside of the tool, as they cannot accidentally open. If a jolt to the knife partially opens a blade, its spring forces it closed again. The typical generally flat handle pieces are what provide support to keep the three pins where they are required to make the individual springs work. The individual spring and three-pin design, however, represents less efficient use of space than the channel-shaped handle design typically used in multipurpose folding hand tools.
What is needed, then, is an improved multipurpose folding tool including a central folding tool easily used, and which does not interfere with the utility of other folding tool bits included in the multipurpose folding tool. It is also desired for such folding scissors to be larger than previously available folding scissors included in a multipurpose folding tool of a comparable size, and that the entire tool in a folded configuration can be easily carried in a person's pocket without causing unnecessary wear of the fabric of the pocket. It is also desired for individual blades of a multipurpose tool to be held securely so that they can safely be located on the outer side of a handle of such tool in its folded configuration. Finally, it is desired for such a multipurpose tool to be simple to assemble and to be able to be assembled in different arrangements.